1. The Field of the Invention
The present invention refers to a process for manufacturing a cooking oven, particularly for food, and to an oven thus obtained.
2. The Relevant Technology
The present context refers to a cooking oven, especially for cooking food, but it is intended that the oven can be used for cooking different substances or materials that require equivalent cooking temperatures or anyway temperatures that can be reached in the oven itself.
The oven is generally wood-fired, by it can also be of a different type, for example fed by pellet or by a gas burner.
In the following, specific reference will be made, in a non-limitative way, to a wood-fired oven, for example used for cooking food such as pizza.
A wood-fired oven of a known type is made substantially by a case which defines an inner compartment: the upper part of the case is generally dome-shaped, while the lower part is a plane surface used to arrange both the substances subject to cooking and the materials used to light the fire, for example wood.
The case comprises an inner refractory part, an intermediate insulating layer, an outer covering part; everything is supported by a base which can be made of various materials (concrete, brick-cement, metal, wood); a chimney is generally present to let the smoke out.
The main characteristics of such an oven are:
pleasant appearance;
resistance to thermal expansion;
short manufacturing time;
impermeability;
lightness.
In this regard, it should be considered that it is necessary to organize its mass production in an effective way, in order to ensure the reproducibility of the result, obtaining a product having reduced encumbrance and weight in order to facilitate its transport and installation, with the possibility of moving it also after the installation.
Currently the outer covering part is made according to different systems:                by masonry with plaster and paint; this operation is actually difficult to reproduce in series with the exact shape and colour, and requires also restrictive hygrometric conditions of the environment, which condition the laying of the plastering, e.g., difference between summer and winter;        by covering with bricks or with a mosaic of small tiles; these operations imply long manufacturing time and their realization has to be given to highly skilled labour, thus an easy mass production is not possible.        
These known solutions are thus characterized by the following inconveniences/disadvantages:                excessive weight; this becomes a limitation to the transport of the finished product, as well as an additional burden for the operators who have to move the parts during the manufacturing;        excessive manufacturing time/cost; manual operations made of several steps and requiring skilled labour;        insufficient impermeableness; as known, mortars are not impermeable to water/atmospheric agents;        aesthetic decay; natural ageing of paint and plaster;        low resistance to thermal expansion; generation of cracks as natural expansion joints when the temperature varies.        
Some example of embodiment of ovens for household appliances, for example described in DE-3713526-A1 and US 2008/246379-A1, which include, in the constitution of the walls, an intermediate layer of flexible material, non-rigid, composed of mineral fiber (glass wool or rock wool) which has the sole function of thermal insulation. This material is not waterproof and cannot stay in contact with atmospheric agents; it is also irritating to skin contact, letting out micro fibers also dangerous to human health, for example if inhaled. These technical solutions are not suitable to solve the problems underlying the present invention.
It is described in US 2009/0320403-A1 an embodiment of a barbecue (outdoor grill) that in a variant presents a hood made of a mono-layer material, such as phenolic resin or fiberglass. This technical solution is not suitable to solve the problems underlying the present invention, as it has characteristics of insufficient strength and reliability against atmospheric agents, and a tendency to flammability.